Significant progress was made in the last reporting period, resulting in five publications. One paper will be highlighted here (Identification of a novel almost neutral micro-opioid receptor antagonist in CHO cells expressing the cloned human mu-opioid receptor. Synapse 64:280-8): """"""""The basal (constitutive) activity of G protein-coupled receptors allows for the measurement of inverse agonist activity. Some competitive antagonists turn into inverse agonists under conditions where receptors are constitutively active. In contrast, neutral antagonists have no inverse agonist activity, and they block both agonist and inverse agonist activity. The mu-opioid receptor (MOR) demonstrates detectable constitutive activity only after a state of dependence is produced by chronic treatment with a MOR agonist. We therefore sought to identify novel MOR inverse agonists and novel neutral MOR antagonists in both untreated and agonist-treated MOR cells. CHO cells expressing the cloned human mu receptor (hMOR-CHO cells) were incubated for 20 h with medium (control) or 10 microM (2S,4aR,6aR,7R,9S,10aS,10bR)-9-(benzoyloxy)-2-(3-furanyl)dodecahydro-6a,10b-dimethyl-4,10-dioxo-2H-naphtho-2,1-cpyran-7-carboxylic acid methyl ester (herkinorin, HERK). HERK treatment generates a high degree of basal signaling and enhances the ability to detect inverse agonists. (35)S-GTP-gamma-S assays were conducted using established methods. We screened 21 MOR """"""""antagonists"""""""" using membranes prepared from HERK-treated hMOR-CHO cells. All antagonists, including CTAP and 6beta-naltrexol, were inverse agonists. However, LTC-274 ((-)-3-cyclopropylmethyl-2,3,4,4alpha,5,6,7,7alpha-octahydro-1H-benzofuro3,2-eisoquinolin-9-ol)) showed the lowest efficacy as an inverse agonist, and, at concentrations less than 5 nM, had minimal effects on basal (35)S-GTP-gamma-S binding. Other efforts in this study identified KC-2-009 ((+)-3-((1R,5S)-2-((Z)-3-phenylallyl)-2-azabicyclo3.3.1nonan-5-yl)phenol hydrochloride) as an inverse agonist at untreated MOR cells. In HERK-treated cells, KC-2-009 had the highest efficacy as an inverse agonist. In summary, we identified a novel and selective MOR inverse agonist (KC-2-009) and a novel MOR antagonist (LTC-274) that shows the least inverse agonist activity among 21 MOR antagonists. LTC-274 is a promising lead compound for developing a true MOR neutral antagonist.""""""""

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Sally, Elliott J; Xu, Heng; Dersch, Christina M et al. (2010) Identification of a novel ""almost neutral"" micro-opioid receptor antagonist in CHO cells expressing the cloned human mu-opioid receptor. Synapse 64:280-8
Iyer, Malliga R; Lee, Yong Sok; Deschamps, Jeffrey R et al. (2010) Probes for narcotic receptor mediated phenomena. 40. N-substituted cis-4a-ethyl-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-8-ols. Bioorg Med Chem 18:91-9
Hsin, Ling-Wei; Chang, Li-Te; Rothman, Richard B et al. (2010) Synthesis and opioid activity of enantiomeric N-substituted 2,3,4,4a,5,6,7,7a-octahydro-1H-benzofuro[3,2-e]isoquinolines. J Med Chem 53:1392-6
Pelotte, Andrea L; Smith, Ryan M; Ayestas, Mario et al. (2009) Design, synthesis, and characterization of 6beta-naltrexol analogs, and their selectivity for in vitro opioid receptor subtypes. Bioorg Med Chem Lett 19:2811-4
Zhang, Yi; Lee, Yong Sok; Rothman, Richard B et al. (2009) Probes for narcotic receptor mediated phenomena. 39. Enantiomeric N-substituted benzofuro[2,3-c]pyridin-6-ols: synthesis and topological relationship to oxide-bridged phenylmorphans. J Med Chem 52:7570-9
Simpson, Denise S; Lovell, Kimberly M; Lozama, Anthony et al. (2009) Synthetic studies of neoclerodane diterpenes from Salvia divinorum: role of the furan in affinity for opioid receptors. Org Biomol Chem 7:3748-56
Kurimura, Muneaki; Liu, Hehua; Sulima, Agnieszka et al. (2008) Probes for narcotic receptor mediated phenomena. 37. Synthesis and opioid binding affinity of the final pair of oxide-bridged phenylmorphans, the ortho- and para-b-isomers and their N-phenethyl analogues, and the synthesis of the N-phenethyl analogues of J Med Chem 51:7866-81
Zezula, Josef; Singer, Lisa; Przybyl, Anna K et al. (2008) Synthesis and pharmacological effects of the enantiomers of the N-phenethyl analogues of the ortho and para e- and f-oxide-bridged phenylmorphans. Org Biomol Chem 6:2868-83